Turbine-driven rotary pumps are already known. These motor-driven pumps are distinguished not only by the types of pumps used and by the model of the turbine, but also by the mutual arrangement of the turbine and pump and, ipso facto, by the mechanical transmission of the movement between these two component parts of the motor-driven pump.
In particular, there are known motor-driven pumps, in which the turbine and the pump are arranged in line, that is to say the axis of the pump and the axis of the turbine are located in the extension of one another. In such motor-driven pumps, at least one of the two (inlet and outlet) connections of the pump is arranged perpendicularly or obliquely relative to the axis of the pump, whereas the second connection is arranged either perpendicularly or obliquely relative to the axis of the pump or in line with the axis of the pump (on that side of the pump located opposite the turbine).
The application DE-A-No. 3,008,334 describes a tangential turbine driving a pump, the rotary body of which is formed by the hollow shaft of the turbine, the machine described in the application DE-A-No. 3,008,334 operating by steam; this steam does not advance in the turbine along the same axis as the pumped fluid.
The document CH No. 465,413 describes a single-axis pump intended for a stationary installation in a nuclear power station. The pump is actuated by a peripheral turbine. However, the rotor of the pump is supported by bearings which encroach on the available cross-section, without any possible mixing between the motive fluid and the pumped fluid.
U.S. Pat. No. 2,113,213 describes cylindrical pumps formed from a small rotary pump and from a concentric turbine. These pumps are intended for operating in wells for extracting water or crude oil from them. These pumps connected in series are placed in a containment and buried under the body of liquid to be pumped. Each pump is equipped with vents at its base. When a pressurized fluid is injected into the containment, it rises via the vents, setting the turbine in rotation and thus actuating the pump. The motive fluid subsequently mixes completely with the liquid pumped in order to rise to the surface.
For some uses, the motor-driven pumps known at the present time all have serious disadvantages; this is especially true of submerged motor-driven pumps used for dredging operations.
In suction dredges, the boom is equipped with a suction pump intended for conveying the dredged materials (mud and/or sand) into the wells of the dredger or into delivery pipes.
Suction can be carried out by means of a motor-driven pump mounted on board the dredger. However, such a system is suitable only for relatively small dredging depths.
For dredging at greater depth, it is usually necessary to employ a submerged motor-driven pump mounted as low as possible on the suction pipe.
Such a submerged motor-driven pump thus works under pressure, and therefore its suction performances are improved. Nevertheless, employing motor-driven pumps known at the present time for such uses presents very serious technical problems attributable particularly to the high weight and large bulk of these motor-driven pumps and of the bent pipelines connected to them. Thus, a submerged motor-driven dredging pump which can be connected to pipes of a diameter of 650 mm represents a weight of the order of 25 tons, a length of 6 m and a lateral bulk of 3 m (including the bent pipes and the frame which is necessary for absorbing the stresses generated during manoeuvring and functioning). The manoeuvring of a dredging head equipped with such a motor-driven pump of known type makes it necessary to use heavy and costly handling appliances.
Another problem arises because of the (mechanically speaking) difficult environment in which these motor-driven pumps have to be used, namely generally aggressive water, such as seawater, laden with salt and with particles of varied granulometry.
To protect the delicate parts of these motor-driven pumps, sealing devices of extremely high performance are generally employed, particularly to protect the rolling bearings and elements of the turbine, thereby proportionately increasing the weight and bulk and also presenting problems of maintenance and heat dissipation.
The motor-driven pump according to the invention, which will be described below, can be used particularly as a submerged motor-driven pump and is especially highly advantageous as a submerged motor-driven pump for dredging and working ocean sediments at great depth. However, the use of the motor-driven pump according to the invention is in no way limited to these particular examples, and it can also advantageously be used as a non-submerged motor-driven pump for the pumping of various liquids or liquids laden with solids (for example, suspensions of ores and/or coal in water).